The impeachments and conviction were perceived by his voters, rightly or wrongly, as cheap political acts done by a corrupt administration. And his opponent, elected in the primaries, was pulled away for actual dementia. If you want to win people over, this is the exact opposite of the way to do it.
So you don't have a way to win if you play by the rules, as long as you can make voters think that whatever you're doing is right and whatever the others are doing is wrong, am I right?
That's like insulting millions of people. I don't think it's that. Trump has to have some appeal that rest of the world is missing. It's not possible to win otherwise.
It's not insulting millions, it's absolutely factual. All the comment you replied to was describing is Trump himself, and millions still voted for the guy. As to WHY they voted for him, I'm sure journalists/analysts/pundits will overflow us with reasons.